Apparatus for treating waste comprising mixed plastic waste

ABSTRACT

A process for treating waste comprising Mixed Plastic Waste is disclosed. The process includes feeding the waste to a pyrolysis reactor, pyrolysing the waste in the pyrolysis reactor to produce a fuel and using the fuel to run a generator to produce electricity.

REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.14/768,066, filed on Aug. 14, 2015, which claims priority to PCT Applic.No. PCT/GB2013/052849, filed on Oct. 31, 2013, which claims priority toU.K. Applic. No. 1303005.1, filed on Feb. 20, 2013, the contents ofwhich are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention concerns processes and apparatus for the treatmentof waste comprising Mixed Plastic Waste.

BACKGROUND OF THE INVENTION

In many countries, waste material is collected and taken to processingcentres or recycling centres. Some categories of waste are separated outand sent to recycling processes, either at the centre or elsewhere. Forexample, waste glass is commonly recycled. Waste that is not recycledmay be sent to landfill or may be burnt, typically to provide eitherheat or electrical energy.

Large amounts of plastic are used in modern goods and packaging andthere is therefore a large quantity of plastic waste, typically termedMixed Plastic Waste, passing through recycling centres. Typically, PETand HDPE are separated out for recycling and the remainder is sent tolandfill. However, landfill may not be a popular option and theretherefore exists a need to find other ways of dealing with Mixed PlasticWaste, either on its own or combined with organic material as MunicipalSolid Waste.

Some solutions have been proposed for Mixed Plastic Waste. For example,Mixed Plastic Waste may be used as a fuel in a power station. However,the cost of electricity generated in such a way may be ten times thecost of electricity generated from a conventional fossil fuel, such asnatural gas. It may also be difficult to use all the heat produced insuch processes and much of it is therefore dissipated in cooling towers.The combination of low efficiency and high capital cost can make suchsolutions unattractive.

Pyrolysis of Mixed Plastic waste has been suggested as a solution.Examples include the use of pyrolysis to create fuel for vehicles,combining pyrolysis with plasma treatment to produce hydrogen andpyrolysis for disposal of plastic waste at sea. However, such processesmay suffer from drawbacks, including the difficulty of producing auniform, high-quality product from a highly variable feed such as wasteand the difficulty of effectively using all the pyrolysis products.

The present invention seeks to mitigate the above-mentioned problems.Alternatively or additionally, the present invention seeks to provide animproved process and apparatus for the treatment of waste comprisingMixed Plastic Waste.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided aprocess for treating waste comprising Mixed Plastic Waste, the processcomprising:

-   -   feeding the waste to a pyrolysis reactor;    -   pyrolysing the waste in the pyrolysis reactor to produce a fuel;        and    -   using the fuel to run a generator to produce electricity.

By pyrolysing the waste, it is possible to create a fuel that powers astandard engine, for example a marine diesel engine attached to agenerator. Such a process may be advantageous in that the capital costof setting up such a process may be lower than for a bespoke combustionprocess.

Mixed Plastic Waste will be understood to be a mixture of wasteplastics. That mixture of plastics could originate from separate streamsof plastics or could originate from a single stream of comingledplastics. In many cases, Mixed Plastic Waste will result from domesticrefuse, such as that traditionally collected in black bags in the UK.Such ‘black bag waste’, or Municipal Solid Waste, will comprise MixedPlastic Waste. It may be that the Municipal Solid Waste is fed to theprocess, but advantageously some separation occurs to remove waste, suchas glass and certain plastics, such as HDPE and PET, that can berecycled before feeding the waste to the process. The separations thatoccur may depend on what other facilities are available to recycle orotherwise use parts of the incoming waste to the facility. Thus, at somefacilities, the waste fed to the process may be Municipal Solid Waste.At some facilities the waste fed to the process may be Mixed PlasticWaste. At some facilities the waste fed to the process may comprisegreater than 10 wt % Mixed Plastic Waste or greater than 20 wt % MixedPlastic Waste. Preferably the waste fed to the process comprises greaterthan 30 wt % Mixed Plastic Waste, more preferably greater than 40 wt %Mixed Plastic Waste, more preferably greater than 50 wt % Mixed PlasticWaste, more preferably greater than 60 wt % Mixed Plastic Waste, morepreferably greater than 70 wt % Mixed Plastic Waste, more preferablygreater than 80 wt % Mixed Plastic Waste and more preferably greaterthan 90 wt % Mixed Plastic Waste. It will be appreciated that wastecomprising a high percentage of Mixed Plastic Waste may be advantageousbecause of a high energy density and also because such waste may bedifficult to treat in other ways and may typically be sent to landfill.It may be that the waste further comprises organic waste. Advantageouslythe waste may contain greater than 70 wt % organic waste. Such waste maycount as biomass for the purpose of government schemes such as theRenewable Obligations Certificate scheme in the UK. In such cases, thewaste preferably comprises greater than 5 wt %, more preferably greaterthan 10 wt %, even more preferably greater than 20 wt % and still morepreferably greater than 25 wt % Mixed Plastic Waste. Advantageously thewaste composition is such that there is sufficient organic waste toqualify as biomass but that substantially the remainder of the waste isMixed Plastic Waste so as to increase the energy density.

Preferably the process comprises passing the fuel through a condenser toform a liquid fraction and a gas fraction and using the liquid fractionof the fuel to run the generator. Using liquid fuel in the generator ispreferable from a cost and simplicity point of view. Liquid fuels may beeasier to store and handle and may be used in a wide variety ofgenerators.

Preferably the process comprises storing the fuel in a buffer tank priorto using it to run the generator. The buffer tank is, for example, atank in which the level of the fuel can vary. In that way, variations inthe rate at which the fuel is produced and consumed can be accommodatedby allowing the reserve of fuel stored in the buffer tank to increase ordecrease. That may be particularly advantageous in a process such as thepresent invention, as it may be most efficient to run the pyrolysisreactor at a constant rate so as to achieve a steady operating state,but the demand for electricity varies through the day. Thus the quantityof fuel in the buffer tank is allowed to increase at times of lowelectricity demand and to decrease at times of high electricity demand.For example, it may be that the fuel is produced continuously and thegenerator is run intermittently. It will be appreciated that continuousproduction means that the process for producing the fuel is runcontinuously over an extended period of time such as days, weeks ormonths.

It may be that the process includes mixing the fuel while it is in thebuffer tank. For example, some of the fuel may be drawn from one part ofthe tank and recirculated to a different part of the tank. If the buffertank comprises multiple tanks, the mixing may be achieved by circulatingthe fuel between the tanks. Mixing the fuel in the buffer tank maysmooth out fluctuations in the properties of the fuel that result fromvariability in the waste fed to the process. That may provide a moreuniform heat of combustion of the fuel over time and may also preventemissions spikes resulting from short-term rises in contamination in thewaste feed.

Preferably, the fuel is stored as a liquid and/or as a solid. The fuelmay thus be stored as a liquid, a solid, or a mixture of a liquid and asolid. It will be appreciated that heavy fuels, such as bunker fuelcommonly used in shipping, may be solid, or a mixture of tarry liquidsand solids, at ambient temperatures and become liquid when warmed, forexample to around 50° C. Thus such fuels may be stored as a liquid, or asolid or a mixture of a liquid and solid depending on temperature. Itwill be appreciated that the tank volume required for liquid/solidstorage may be significantly smaller than for storing an equivalentamount of fuel (in energy terms) as a gas. Liquid/solid storage may alsobe intrinsically safer. The process may comprise warming the fuel in thebuffer tank so as to transfer, for example pump, it to the generator.The warming may be achieved using heat from the generator, when it isrunning, or by using an external source of heat, for example at startup.

The buffer tank may comprise a tank container, for example a tankcontainer compatible with ISO standards for intermodal tank containers.Preferably the buffer tank comprises a so-called “20 ft” tank container.Thus the buffer tank may be 6.1 m long and 2.44 m wide and high andmounted in an ISO compatible intermodal container frame. The volume ofthe tank may be from 14,000 to 27,000 litres. In some embodiments thebuffer tank may comprise a plurality of tank containers. Such anarrangement may be advantageous in that a plurality of container tanksmay be simpler and cheaper to manufacture and deliver than a singlelarge tank and in that capacity may be straightforwardly added byproviding further container tanks. Multiple container tanks may alsoprovide for flexibility in maintenance and operation and be safer than asingle large tank.

Preferably the process comprises filtering the fuel to remove chemicalcontaminants. Emissions from generators may be subject to strictcontrols and it is possible that fuel produced from waste may containsignificant levels of chemical contamination. For example, PVC in theplastic waste may mean that there are undesirable levels of chlorine inthe fuel as it exits the pyrolysis reactor.

Other chemical contaminants include fluorine and sulphur. By filteringthe fuel, the chemical contamination can be removed before the fuel isused in the generator. The filtering may therefore remove chemicalsassociated with poor emissions, for example emissions that wouldcontravene the Waste Incineration Directive. The fuel may be filtered inthe gas phase. That is, the fuel may exit the pyrolysis reactor as a gasand be filtered in the gas phase before the fuel is condensed. It willbe appreciated that the fuel is filtered before it is used in thegenerator. Thus the filtration occurs before combustion. There may be asignificant advantage in filtering the fuel after the pyrolysis butbefore it is used in the generator. Pyrolysis breaks down the chainlengths of the hydrocarbons in the plastics, resulting in smallermolecules. Combustion, on the other hand combines the hydrocarbons withoxygen, typically from air, which results in a large volume of exhaustgas. The result is that the volume of fuel gas exiting the pyrolysisreactor may be significantly lower than the volume of gas that would beproduced by combustion, either of the waste or the subsequent combustionof the fuel in the generator. By cleaning the pyrolysis product thevolume of gas to be filtered and cleaned may be lower than the volume ofgas that would need to be filtered and cleaned in a combustion exhaust;as a result smaller filters may be used with associated advantages interms of capital and operating costs.

Preferably the process includes storing the waste in a vessel prior tofeeding the waste to the pyrolysis reactor, wherein the waste is blendedwhilst stored in the vessel. It will be appreciated that waste collectedtends to vary in composition from hour to hour and day to day. That maypresent a particular challenge when trying to convert the waste into adesired product, as the composition of the waste feed may affect thecomposition and attributes of the product. Even if sophisticated controlof the process to adjust operating conditions to compensate for thevariable composition of the waste is available, it can still beadvantageous to try to minimise the variations in waste composition. Bystoring the waste in a blended storage tank, variations in compositionmay be to some extent averaged out. Even if such storage does notcompletely eliminate variations, it may smooth the rate at which thecomposition changes, and may therefore allow more time for the controlsystem to apply adjustments.

Preferably the waste is dried in a dryer prior to being fed to thepyrolysis reactor. The dryer may reduce the water content of the wasteto less than 5 wt %, preferably less than 3 wt %. The dryer may reducethe water content of the waste to between 2 and 3 wt %. When the wasteis fed to the pyrolysis reactor, it is heated to the reactiontemperature. Heating any water that is in the waste requires extraenergy and therefore it may be advantageous to remove the water in adryer before the waste is heated. If the fuel is being stored as aliquid, any water in the waste is heated to form steam in the reactorand then condensed again to water in the condenser, resulting in a wasteof energy.

Preferably the temperature in the pyrolysis reactor is controlled so asto produce a fuel comprising C₅ to C₁₀₀ hydrocarbons. The mean chainlength of the fuel, based on the number of molecules, is preferably inthe range C₅ to C₄₀, more preferably in the range C₁₀ to C₂₀. It may bethat 80 wt % of the fuel consists of hydrocarbons with a chain length inthe range C₅ to C₄₀, more preferably in the range C₅ to C₂₀, morepreferably in the range C₁₀ to C₂₀. Preferably the hydrocarbons in thefuel have a chain length greater than C₅. That may be achieved bypassing the fuel through a condenser and separating off the part of thefuel that remains as a gas following the condensation (the gasfraction). The liquid fraction may then be used as the fuel and the gasfraction used elsewhere in the process or the host facility.

For example, the fuel may be bunker fuel. It will be appreciated thatthe composition of the fuel may be selected based on the generator usedin the process. The hydrocarbon chain length of the fuel affects theheat of combustion of the fuel. Shorter chain lengths result in a higherheat of combustion. However, at very short chain lengths (for example,less than C₅), a small change in chain length can result in a largechange in heat of combustion. That can result in control challenges, as,for example, a small decrease in the average chain length of the fuelcan lead to a large increase in the energy released when the fuel iscombusted and can therefore cause engine failures. Conversely, at verylong chain lengths (for example, greater than C₄₀) a large change in theaverage chain length may be required to produce a significant change inheat of combustion. That may lead to control challenges in that largecontrol variations may be needed to produce a noticeable effect on thefuel. The average chain length of the fuel is therefore preferablyselected so as to be at a value where changes in the fuel chain lengthproduce a sensible change in the heat of combustion in the fuel. In thatway control variations can be used to alter the heat of combustion ofthe fuel as necessary, but short-term deviations outside the controlrange do not have catastrophic consequences.

As mentioned above, control of the process may be challenging due to thevariability of the waste fed to the process. The process may becontrolled by monitoring the waste input or by monitoring the generatorbut the process is preferably controlled by monitoring an attribute ofthe fuel and adjusting the temperature and/or the residence time of thepyrolysis reactor in response to the measured attribute of the fuel soas to maintain that attribute within a desired range. It may be that thetemperature of the reactor is adjusted. It may be that the residencetime of the reactor is adjusted, for example by adjusting the flowratethrough the reactor. It may be that both the temperature and theresidence time of the reactor are adjusted. Preferably the attribute isrelated to the heat of combustion, or the calorific value, of the fuel.For example, the attribute may be the heat of combustion of the fuel orit may be a parameter whose value is dependent on the heat of combustionof the fuel. The attribute of the fuel could be measured in the buffertank, but is preferably measured at the inlet to the tank so as to avoidthe large volume of fuel in the tank slowing the response time of thecontrol system. By monitoring the fuel entering the tank, the controlsystem can detect variations in the process more rapidly and apply anynecessary adjustment. For example, if the monitor detects that the heatof combustion of the fuel entering the buffer tank is falling, thecontrol system can increase the heat of the reactor or increase theresidence time in the reactor. That may be achieved by feeding a greaterquantity of the fuel to the burners heating the reactor or by reducingthe flowrate through the reactor. Conversely, if the monitor detectsthat the heat of combustion of the fuel is rising too high, thetemperature in the reactor can be decreased or the residence time in thereactor can be decreased.

The heat of combustion of the fuel is preferably controlled using asolvent monitor. Such a system may involve providing a hydrogen flame,feeding a sample of the fuel into the flame and recording the flametemperature. The heat of combustion of the flame may be related to thedifference between the flame temperature with the fuel added and thetemperature of the hydrogen flame but the process may be controlled morestraightforwardly by controlling the process so as to achieve a flametemperature with the fuel added within a desired range. For example, athermocouple may be provided to monitor the flame temperature and theoutput from the thermocouple used as an input to the control process forthe reactor. Such a system may be a cheap and simple option formonitoring the fuel quality. By monitoring the fuel quality the responsetime of the control system may be improved. For example, if the controlsystem monitors the generator operation, by the time a decrease in poweris observed, a large quantity of sub-standard fuel may already have beenproduced. That may be particularly the case where the fuel is stored ina buffer tank. Furthermore, it may be more straightforward to monitorthe fuel quality, since the fuel is a fluid, than it is to monitor thecomposition of the incoming waste.

Heat of combustion is a well-known attribute and the skilled person canmeasure the heat of combustion. For example, the heat of combustion ofsolids may be measured using methods such as ISO1928:2009 and the heatof combustion of liquid hydrocarbons may be measured using methods suchas ASTM D4809. It may be that the heat of combustion of the waste isaround 30 MJ/kg, for example in the range 25 MJ/kg to 35 MJ/kg.Preferably the process is controlled so as to produce a fuel having aheat of combustion less than 45 MJ/kg. More preferably the process iscontrolled so as to produce a fuel having a heat of combustion in therange 42 MJ/kg to 45 MJ/kg, even more preferably 44 MJ/kg to 45 MJ/kg. Afuel with a heat of combustion in that range may be at a point on acurve of heat of combustion against average chain length wherecontrolled variations in the heat of combustion can be achieved byvarying the temperature and/or residence time of the pyrolysis reactorso as to vary the average chain length. Fuels below that range may be ina region of the curve where undesirably large changes in reactorconditions are needed to vary the heat of combustion and fuels abovethat range may be in a region where unavoidable variations in thereactor conditions result in undesirably large fluctuations in the heatof combustion. Nevertheless, it may still be advantageous to operate inthe higher or lower regions in some circumstances. For example, at lowerheats of combustion the process may be very stable and at higher heatsof combustion more power may be available.

The temperature in the reactor may, for example, be in the range 400° C.to 600° C. The reactor may be a fluidised bed reactor, with thefluidised bed having a mass of 2.5 to 8 tonnes, preferably 2.5 to 5tonnes, more preferably 2.5 to 3.5 tonnes. The reactor or the fluidisedbed may have an aspect ratio (height:width) of around 1:1, for examplein the range 0.5:1 to 1:2, preferably in the range 0.8:1 to 1:1.2. Sucha reactor size, shape and temperature may allow efficient treatment ofthe waste.

Preferably a product from the pyrolysis reactor is combusted to heat afluid, the fluid being used to heat the pyrolysis reactor. The fluid maycomprise the fuel. For example, a portion of the fuel output stream fromthe pyrolysis reactor may be directed through a heater, preferably anindirect heater, and back into the pyrolysis reactor.

The product from the pyrolysis reactor may comprise the fuel. Theproduct from the pyrolysis reactor may comprise part of the fuel outputstream from the pyrolysis reactor that is not sent to the generator. Forexample, if the process comprises passing the fuel through a condenserto form a liquid fraction and a gas fraction and using the liquidfraction of the fuel to run the generator, the product combusted to heatthe fluid used to heat the pyrolysis reactor may comprise the gasfraction. It may be that the gas fraction is sufficient to heat thepyrolysis reactor but it may be that extra heat is needed, in which caseit may be that the gas fraction is supplemented by some of the liquidfraction. The gas fraction is preferably supplemented by a stream of thefuel product from the pyrolysis reactor that is taken from upstream ofthe condenser. In that way energy is not wasted condensing the fuel onlyto combust it again immediately to heat the reactor. It may be that thegas fraction exceeds the amount of heat required to heat the pyrolysisreactor. In such cases the excess gas may be used elsewhere or flared.

It may be that the product from the pyrolysis reactor combusted to heatthe fluid that is used to heat the pyrolysis reactor is a by-product ofthe pyrolysis. For example, the product may be char. For example, thepyrolysis reactor may be a fluidised bed reactor and the process maycomprise removing a portion of the fluidised bed that has become atleast partially coated in char from the reactor, separating the char,returning the portion of the fluidised bed to the reactor and combustingthe char to heat a fluid that is used to heat the reactor. By combustingthe char to provide the heat, none of the fuel product is used forheating the reactor so the process can provide more energy through thegenerator.

By combusting part of the product to provide heat, the process does notrequire a separate fuel source for normal operation. The skilled personwill appreciate that for start-up a separate source of heat may still berequired. By using combustion of the product to heat a further streamcomprising the fuel, with the further stream being introduced into thepyrolysis reactor, the combustion products may be kept out of thereactor. Such an indirect heating system may allow combustion to provideheat, without the reactor becoming contaminated with combustionproducts.

Preferably the fuel is used to run a first generator and a secondgenerator. For example, the first generator may be run continuously andthe second generator run intermittently according to grid demand. It maybe that the first generator is smaller than the second generator. It maybe that the first generator is larger than the second generator. Forexample, the first generator may be used to provide continuous power tothe host facility in which the process operates and the second generatorcould be used to produce power to sell to the grid. Preferably the firstgenerator is sized according to the heat or electricity demand of thehost facility. Preferably the second generator has a short start-upcycle, for example starting up in less than 10 minutes, so as to be ableto provide reserve power to the grid at short notice. The ability to actas part of the grid's reserve may be advantageous in terms of the pricesthat the grid will pay. It may be that the first generator forms part ofa control system, with the generator's performance being monitored andthe measured performance being used to control the operating conditions,for example the temperature and residence time of the pyrolysis reactor,of the process.

The generators may, for example, be turbines, preferably gas turbines,but are preferably internal combustion engines attached to generators.For example, the engine may be a marine diesel engine, which may, forexample, run on bunker fuel. In such a case, the control system could becalibrated so as to produce bunker fuel in the buffer tank. Combiningthe use of bunker fuel in a marine diesel with a step of filtering thefuel before it is used in the marine diesel can be advantageous as thecleaned fuel may mean that the emissions from the marine diesel engineare reduced. That may be particularly advantageous, as bunker fuel maybe considered to be highly polluting and therefore require expensiveexhaust clean-up unless the filtering is used.

Preferably the process treats from 5,000 to 20,000 tonnes per year ofwaste, more preferably 5,000 to 10,000 tonnes per year of waste and evenmore preferably 6,000 to 8,000 tonnes per year of waste. For example itmay be that the process treats 7,000 tonnes per year of waste. Processesof those sizes can be conveniently combined with existing recyclingfacilities so as to treat Mixed Plastic Waste on-site, rather thanhaving to transport the waste to another, larger facility such as apower station. Transporting waste uses energy and may therefore reduceor eliminate the environmental benefit of subsequent treatment.Preferably the process produces from 1.8 to 10 MW, more preferably 1.8to 5 MW and even more preferably 2.1 to 4 MW. For example, it may bethat the process produces from 2.5 to 3.5 MW of electricity.

Preferably the process includes cooling the exhaust from the generatorby heat exchange with an air stream, wherein at least part of the airstream is used to provide heat elsewhere in the process or elsewhere inthe host facility in which the process is carried out. For example, theair stream may be used to provide heat in the dryer, thus improving theoverall efficiency of the process.

The generator may be cooled by heat exchange, for example indirect heatexchange with a fluid stream and at least part of that fluid stream maythen be used to provide heat to another part of the process, for examplethe dryer, or to another process in the host facility. Preferably thegenerator is cooled by heat exchange with a water stream, wherein atleast part of the water stream is used to provide heat elsewhere in theprocess or elsewhere in the host facility.

Preferably the pyrolysis reactor is a fluidised bed reactor. Forexample, the pyrolysis reactor may contain a fluidised bed of particles,such as sand, and a distributor for feeding a fluidisation medium intothe reactor. The fluidisation medium may, for example, be recycledpyrolysis product, which may have been heated in order to supply energyto the pyrolysis reactor. The distributor design may be an importantpart of the fluidised bed design so as to achieve a uniform distributionof the fluidising medium across the bed. Moreover, the fluidised bed mayaccumulate contaminants over time and the particles of the bed, forexample sand, may need cleaning. For example, tar, char or coke mayaccumulate on the particles. The cleaning could be achieved by shuttingdown the reactor and removing the particles, but it is advantageouslyperformed on-line by a recirculation of the particles through a cleaningsystem. The distributor is preferably configured so as to allow aportion of the fluidised particles to fall through the distributor andthe process preferably comprises removing a portion of the particlesthat have fallen through the distributor, cleaning the particles andfeeding the particles back into the reactor. In that way a continuousrecirculation of the particles through the cleaning apparatus may beachieved. For example, the distributor may comprise an array of ductswith orifices, for example in their surface, the ducts being configuredsuch that the fluidising medium is fed to the ducts and exits the ductsthrough the orifices into the reactor, wherein the array of ducts isconfigured such that the particles can fall between the ducts. The ductsmay for example be arranged in a row or a grid, with the spacing betweenthe ducts being selected so as to allow the particles to pass betweenthe ducts. It will be appreciated that steps may be taken to prevent theparticles that are falling from the fluidised bed falling into, andblocking, the orifices. The orifices may, for example, be in theunderside of the ducts. In another example, the orifices may comprise anozzle comprising a cap to prevent particles blocking the orifice.

It will be appreciated that using the heat from the generator mayprovide significant advantages in terms of efficiency. As well asproviding electrical power to the host facility, the generator can alsosupply heat to the host facility. Such a ‘combined heat and power’approach allows the energy in the fuel to be efficiently transformedinto useful energy for the host facility. Thus, in a broad aspect of theinvention there is provided a process for treating waste comprisingMixed Plastic Waste at a host facility, the process comprising:

-   -   providing an apparatus comprising a pyrolysis reactor and a        generator at the host facility;    -   feeding the waste to a pyrolysis reactor;    -   pyrolysing the waste in the pyrolysis reactor to produce a fuel;        and    -   using the fuel to run a generator to produce energy.

It may be that the energy is electrical energy; that is the generator isrun to produce electricity. It may be that the energy is heat energy.Preferably the energy is both electrical and heat energy. Such a‘combined heat and power’ approach may be advantageous because thegenerator may require cooling even if being run to produce electricityand it may therefore be advantageous to make use of the heat energy aswell. The host facility may be a site having energy demands. Preferablythe energy is used within the host facility. For example, the hostfacility may be a recycling plant and the energy may be used in otherparts of the recycling process.

It will be appreciated that controlling the process is an inventivefeature of the process in its own right and may be particularlyimportant when there is significant variability in the waste feed. Thus,in a second aspect of the invention there is provided a process fortreating waste comprising Mixed Plastic Waste, the process comprising:

-   -   feeding the waste to a pyrolysis reactor;    -   pyrolysing the waste in the pyrolysis reactor to produce a fuel;    -   monitoring an attribute of the fuel; and    -   adjusting the temperature and/or residence time of the pyrolysis        reactor in response to the measured attribute of the fuel so as        to maintain the attribute within a desired range.

Preferably the attribute is related to the heat of combustion of thefuel.

The design of the distributor is an inventive feature of the process inits own right. Thus, in a third aspect of the invention there isprovided a process for treating waste comprising Mixed Plastic Waste,the process comprising:

-   -   feeding the waste to a pyrolysis reactor, the pyrolysis reactor        being a fluidised bed reactor; and    -   pyrolysing the waste in the pyrolysis reactor to produce a fuel;    -   wherein the pyrolysis reactor contains a fluidised bed of        particles and a distributor for feeding a fluidisation medium        into the reactor, wherein the distributor is configured such        that the particles can fall through the distributor and wherein        the process comprises removing a portion of the particles that        have fallen through the distributor, cleaning the particles and        feeding the particles back into the reactor.

Heating the pyrolysis reactor is an inventive feature of the process inits own right. Thus, according to a fourth aspect of the invention thereis provided a process for treating waste comprising Mixed Plastic Waste,the process comprising:

-   -   feeding the waste to a pyrolysis reactor, for example a        fluidised bed reactor; and    -   pyrolysing the waste in the pyrolysis reactor to produce a fuel;        and    -   combusting a product from the pyrolysis reactor to heat a fluid,        and feeding the fluid into the pyrolysis reactor so as to heat        the pyrolysis reactor.

It may be that the product is a by-product, for example char. It may bethat the product comprises the fuel. It may be that the productcomprises a part of the fuel output stream from the pyrolysis reactorthat is not used to run the generator.

The processes of the above aspects of the invention are particularlysuited to use in small to moderate sized recycling facilities, wherethey complement the facilities already present. For example, theelectricity and heat generated by the process of the above aspects ofthe invention can be used to power recycling operations at the centre.Thus, according to a fifth aspect of the invention there is provided aprocess for recycling waste material, the process comprising a processfor treating waste comprising Mixed Plastic Waste according to any ofthe above aspects of the invention.

It will be appreciated that the process of the invention is carried outat a site, or host facility, for example a recycling or waste processingfacility. According to a sixth aspect of the invention there is providedan apparatus for treating waste comprising Mixed Plastic Waste, theapparatus comprising:

-   -   a pyrolysis reactor for pyrolysing the waste to produce a fuel;        and    -   a generator configured to run on the fuel to produce        electricity.

Preferably the apparatus comprises a condenser downstream of thepyrolysis reactor and upstream of the generator for condensing the fuelprior to using it to run the generator.

Preferably the apparatus comprises a buffer tank downstream of thepyrolysis reactor and upstream of the generator for storing the fuelprior to using it to run the generator.

Preferably the apparatus comprises a filter system downstream of thepyrolysis reactor and upstream of the generator for filtering the fuelto remove chemical contaminants.

Preferably the apparatus includes a storage vessel upstream of thepyrolysis reactor for storing the waste prior to feeding the waste tothe pyrolysis reactor, wherein the storage vessel comprises a blendingsystem for blending the waste stored in the vessel.

Preferably the apparatus comprises a dryer upstream of the pyrolysisreactor for drying the waste.

Preferably the apparatus comprises:

-   -   a monitor, preferably a solvent monitor, for monitoring an        attribute of the fuel; and    -   a controller for adjusting the temperature and/or residence time        of the pyrolysis reactor in response to the measured attribute        of the fuel so as to maintain the attribute within a desired        range. Preferably the attribute is related to the heat of        combustion of the fuel.

Preferably the apparatus comprises a combustor to combust a product fromthe pyrolysis reactor to heat a fluid that is fed into the pyrolysisreactor to heat the pyrolysis reactor. It may be that the product is aby-product, for example char. It may be that the product comprises thefuel. It may be that the product comprises a part of the fuel outputstream from the pyrolysis reactor that is not used to run the generator.

Preferably the generator comprises an internal combustion engine, forexample a marine diesel engine.

Preferably the apparatus is sized and configured to treat from 5,000 to20,000 tonnes per year of waste, more preferably 5,000 to 10,000 tonnesper year of waste and even more preferably 6,000 to 8,000 tonnes peryear of waste.

Preferably the apparatus is sized and configured to produce from 1.8 to10 MW, more preferably 1.8 to 5 MW and even more preferably 2.1 to 4 MW.For example, it may be that the process produces from 2.5 to 3.5 MW ofelectricity.

Preferably the pyrolysis reactor is a fluidised bed reactor.

Preferably the pyrolysis reactor is configured to contain a fluidisedbed of particles and the apparatus comprises a distributor for feeding afluidisation medium into the reactor, wherein the distributor isconfigured such that the particles can fall through the distributor andwherein the pyrolysis reactor includes an outlet, such as a rotaryvalve, through which, in use, a portion of the particles that havefallen through the distributor can be removed, an apparatus for cleaningthe particles and an inlet through which the cleaned particles can befed back into the reactor. The inlet is preferably above the distributorin the fluidised bed reactor.

Preferably the distributor comprises an array of ducts with orifices intheir surface, wherein the ducts in the array are spaced apart suchthat, in use, the particles can fall between the ducts.

According to a seventh aspect of the invention there is provided anapparatus for treating waste comprising Mixed Plastic Waste, theapparatus comprising:

-   -   a pyrolysis reactor for pyrolysing the waste to produce a fuel;    -   a monitor for monitoring an attribute of the fuel; and    -   a controller for adjusting the temperature and/or residence time        of the pyrolysis reactor in response to the measured attribute        of the fuel so as to maintain the attribute within a desired        range.

Preferably the attribute is related to the heat of combustion of thefuel.

According to an eighth aspect of the invention there is provided anapparatus for treating waste comprising Mixed Plastic Waste, theapparatus comprising:

-   -   a pyrolysis reactor for pyrolysing the waste to produce a fuel,        the pyrolysis reactor being a fluidised bed reactor;    -   wherein the pyrolysis reactor is configured to contain a        fluidised bed of particles and wherein the apparatus comprises a        distributor for feeding a fluidisation medium into the reactor,        wherein the distributor is configured such that the particles        can fall through the distributor and wherein the pyrolysis        reactor includes an outlet through which, in use, a portion of        the particles that have fallen through the distributor can be        removed, an apparatus for cleaning the particles and an inlet        through which the cleaned particles can be fed back into the        reactor.

According to a ninth aspect of the invention there is provided anapparatus for treating waste comprising Mixed Plastic Waste, theapparatus comprising:

-   -   a pyrolysis reactor for pyrolysing the waste to produce a fuel,        for example a fluidised bed reactor; and    -   a combustor to combust a product from the pyrolysis reactor to        heat a fluid that is fed into the pyrolysis reactor to heat the        pyrolysis reactor.

It may be that the product is a by-product, for example char. It may bethat the product comprises the fuel. It may be that the productcomprises a part of the fuel output stream from the pyrolysis reactorthat is not used to run the generator.

Advantageously the apparatus is portable in that it is constructed insuch a way that it can be broken down into a number of modules, each ofwhich is transportable. For example elements of the apparatus may beindividually mounted in frames compatible with the ISO standards forfreight containers to create modules that can be individuallytransported using equipment designed for the handling of freightcontainers. The modules may be made at a factory facility and thenshipped to the location in which they are to be used, where they areconnected together with other modules to form the apparatus. That may bea cost effective system of providing the apparatus at the location andmay reduce the need for skilled labour at the location to install theapparatus. In some examples, the apparatus may be employed at a firstlocation to treat a volume of waste stored at the first location, beforebeing dismantled and transported to a second location to treat a volumeof waste stored at that second location. In that way, a number of smallwaste collection facilities may be serviced on a rotational basis,rather than shipping the waste to a central location. In some examplesthe apparatus may be mounted in a portable manner, for example on aship, so that the apparatus can be operated whilst the ship is inmotion. Advantageously such an apparatus could be used to treat largeislands of plastic waste that accumulate in the oceans.

According to a tenth aspect of the invention there is therefore providedan apparatus for treating waste comprising Mixed Plastic Waste, theapparatus comprising:

-   -   a pyrolysis reactor for pyrolysing the waste to produce a fuel,        for example a fluidised bed reactor;        wherein the pyrolysis reactor is mounted in a frame having        fittings that are compatible with the load handling equipment        used to transport freight containers.

The frame may be part of a freight container; that is, the reactor maybe mounted in a freight container, but preferably the frame is an openframe, in that the module has the shape of a freight container andcomprises structural members along the module edges but does not includepaneling to close the faces of the module. Such a frame may be lighterand allow better access to the equipment.

Preferably the apparatus comprises a generator configured to run on thefuel to produce electricity; wherein the generator is mounted in a framehaving fittings that are compatible with the load handling equipmentused to transport freight containers.

Preferably the apparatus comprises a buffer tank downstream of thepyrolysis reactor and upstream of the generator for storing the fuelprior to using it to run the generator; wherein the buffer tank ismounted in a frame having fittings that are compatible with the loadhandling equipment used to transport freight containers.

The apparatus may comprise further elements, for example: filters,dryers or storage tanks with blending systems, as described above inrelation to aspects one to nine of the invention. Some or all of thoseelements may also be mounted in frames having fittings that arecompatible with the load handling equipment used to transport freightcontainers. It may be that, in some frames, more than one element ismounted. Such an arrangement may be advantageous in reducing the numberof frames that need transporting. It may be that each element is mountedin a separate frame. Such an arrangement may be advantageous in allowingexchangeability of components.

According to an eleventh aspect of the invention there is provided arecycling plant for recycling waste material, the plant comprising anapparatus for treating waste comprising Mixed Plastic Waste according toany of the above aspects of the invention. Preferably the recyclingplant is sized to process from 5,000 to 100,000 tonnes of waste materialper year. As such the recycling plant may be an existing facilityserving a city or a group of towns and the apparatus may be installed atthe plant to provide a process for treating Mixed Plastic Waste, whichotherwise would have been sent away from the plant to be treated orlandfilled elsewhere.

It will of course be appreciated that features described in relation toone aspect of the present invention may be incorporated into otheraspects of the present invention. For example, the apparatus of theinvention may incorporate any of the features described with referenceto the process of the invention and vice versa. Similarly any process orapparatus aspect of the invention may incorporate any of the featuresdescribed with reference to other process or apparatus aspects of theinvention.

DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described by way ofexample only with reference to the accompanying schematic drawings ofwhich:

FIG. 1 is a schematic view of an apparatus according to a firstembodiment of the invention;

FIG. 2 is a schematic view of a distributor in the pyrolysis reactor ofFIG. 1; and

FIG. 3 is a schematic view of a control system for the apparatus of FIG.1.

DETAILED DESCRIPTION

In FIG. 1 an apparatus 1 for treating waste comprising Mixed PlasticWaste has a loading conveyer 3. The loading conveyer 3 feeds a de-waterpress 5, the outlet of which is arranged above a conveyer 7 to ashredder 9. The outlet of the shredder 9 is directed at a conveyer 11 toa filter 13, which includes a ferrous and non-ferrous filter. The outletof the filter 13 is connected to a dryer 15 and the outlet of the dryer15 is connected to a storage tank 17. The storage tank 17 is fed byconveyer 19 and comprises a blending system. The outlet of storage tank17 is connected via line 21 to the inlet of a fluidised bed pyrolysisreactor 23. The reactor 23 contains sand, which forms the fluidised bed.The bottom of the reactor 23 has a valve connected, via line 25, to acleaner 27, which in turn is connected, via line 29 to a hopper 31. Thehopper 31 feeds into the reactor 23. The outlet from the top of thereactor 23 is connected to hot gas filter 33, the outlet of which isconnected, via line 35, to condenser 37.

From line 35, a branch 39 is connected, via pump 41, to heat exchanger43. From heat exchanger 43 a line 45 feeds into reactor 23. Fuel supplyline 49 runs from line 35 to burner 53. Fuel supply line 47 runs fromthe top of condenser 37 to burner 51. Burners 51 and 53 are mounted onheat exchanger 43.

Condenser 37 is on top of, and feeds into, buffer tank 55. An outlet 57from the buffer tank 55 is connected, via pump 59, to engine 61, whichis attached to generator 63. Engine 61 and generator 63 together form agenerator to produce electricity and heat. Cooling water loop 65 runsthrough engine 61 and heat exchanger 67. Water line 69 passes throughheat exchanger 67 and on to another part of the plant. The exhaust 71from the engine 61 passes through heat exchanger 73 and then filter 75before being exhausted to the atmosphere. Air line 77 passes throughheat exchanger 73 and on to another part of the plant.

In FIG. 2, the lower part of the reactor 23 has a distributor 79. Thedistributor 79 is at the bottom of the fluidised bed 85. The distributor79 comprises an array of ducts 81 a-e with orifices 89 a-e in theirupper surface. The orifices comprise nozzles 83 a-e, which sit on top ofthe orifices. The ducts 81 a-e are spaced apart such that the gapsbetween the ducts are large enough for particles from the fluidised bed85 to fall through. At the bottom of the reactor 23 there is a valve 87leading to line 25.

In FIG. 3 a solvent monitor 91 is mounted on line 35. The solventmonitor 91 is in communication with reactor management system 93.Temperature monitor 99 is in reactor 23 and is also in communicationwith reactor management system 93. Reactor management system 93 is incommunication with gas burner control 95, which controls burners 51 and53, and material feed control 97, which controls the feed rate from line21 into reactor 23.

In use, 7000 tonnes per year of waste, in this embodiment Mixed PlasticWaste, is loaded continuously onto the loading conveyer 3. The wastetravels up the loading conveyer 3 and drops into the de-water press 5,where the pressing action forces water out of the waste. The driedwaste, which has a moisture content of about 15% by weight exits thede-water press 5 and is conveyed along conveyer 7 and into the shredder9, where it is shredded. The shredded waste exits shredder 9 and travelsalong conveyer 11 to filter 13. Filter 13 comprises ferrous andnon-ferrous filters and removes metallic contaminants from the waste.The de-watered, shredded and filtered waste then passes into dryer 15,where the water content is reduced to about 2-3 wt %. The dryer 15 ispowered by heat from hot water line 69 or hot air line 77, or both. Onexiting the dryer 15, the dry, shredded, filtered waste is stored instorage tank 17. Whilst in the storage tank 17, the waste is constantlyblended by withdrawing a portion of the waste from the bottom of one endof storage tank 17 and recirculating it to conveyer 19 to beredistributed across the top of storage tank 17. With waste also beingcontinuously added to and withdrawn from storage tank 17 to feed theprocess, the effect of the blending recirculation is to smoothvariations in the composition of the waste over time.

Waste is withdrawn from the storage tank 17 along line 21 and fed to thefluidised bed pyrolysis reactor 23. On entering the reactor 23, thewaste is heated to around 400 to 600° C. The heating is achieved byfeeding a hot stream into the reactor 23 along line 45. That hot streamcomprises pyrolysis product drawn from line 35, along line 39, andheated indirectly by combustion of a portion of the pyrolysis product,which is also drawn from line 35, along line 47 or 49. The portion ofthe pyrolysis product combusted is normally drawn along line 47 from thetop of the condenser 37 and comprises the gas fraction of the fueloutput stream 35 from the pyrolysis reactor 23 that does not condense inthe condenser 37. When extra fuel is required, it is drawn directly fromthe fuel output stream in line 35 along line 49. In that case, some ofthe fuel product that would in normal circumstances be used to run theengine 61 is being used to heat the pyrolysis reactor 23.

The heated waste undergoes a pyrolysis reaction that decreases thehydrocarbon chain lengths to around C₅ to C₁₀₀. The process is carriedout in a fluidised bed 85 of sand, which results in good mixing and eventemperature across the reactor 23. The sand becomes contaminated withby-products over time. To prevent excessive build-up, a portion of thesand is continuously withdrawn from the bottom of reactor 23 along line25 and cleaned in cleaner 27. The cleaned sand is reheated and fed backinto the reactor 23 via line 29 and hopper 31.

The products of the pyrolysis reaction exit the top of the reactor 23and pass through hot gas filter 33. The filter 33 removes chemicalcontaminants such as chlorides (resulting from PVC in the Mixed PlasticWaste) and sulphates, resulting in a clean fuel gas which flows alongline 35 and is condensed into buffer tank 55 by condenser 37.

The quality of the fuel in line 35 is monitored continuously by solventmonitor 91. Solvent monitor 91 measures a flame temperature resultingfrom burning a sample of the fuel in a hydrogen flame. The temperatureof the flame can be related to the heat of combustion of the fuel.Solvent monitor 91 communicates the flame temperature to reactormanagement system 93 by means of an electronic signal from athermocouple in solvent monitor 91. Reactor management system 93 alsoreceives a signal from temperature monitor 99 in the pyrolysis reactor23. Reactor management system 93 responds to changes in the flametemperature of solvent monitor 91 by adjusting the operation of burners51 and 53 and the feed rate from line 21 into pyrolysis reactor 23 bymeans of gas burner control 95 and material feed control 97. In thatway, reactor management system 93 can adjust the temperature and/or theresidence time of the pyrolysis reactor 23. Thus, if solvent monitor 91detects that the flame temperature is falling, indicating that thequality of the fuel is falling, the reactor management system 93increases the temperature in the reactor 23, or increases the residencetime in the reactor 23, or both. The average chain length of the fuel inthe output from the reactor 23 should then decrease and the quality ofthe fuel increase. Conversely, if the solvent monitor 91 indicates thatthe heat of combustion of the fuel is rising, which could cause problemsin engine 61, the reactor management system 93 can reduce thetemperature or residence time or both of the reactor 23 so as todecrease the pyrolysis of the waste and maintain the flame temperatureof the solvent monitor 91 within its desired range.

The level of fuel in buffer tank 55 can be allowed to increase anddecrease. Thus the reactor 23 can be run continuously at a constantsteady state, but the fuel can be used in a discontinuous way or at avarying rate. At night, when the demand for electricity is low, thelevel of fuel in the buffer tank 55 rises, whilst at times of peakdemand the level of fuel in the buffer tank 55 can be allowed todecrease.

The fuel in buffer tank 55 is continuously recirculated so as to mix thefuel and smooth temporal variations in the quality of the fuel enteringthe tank 55 from condenser 37. The recirculation also helps to smoothspikes in contaminant concentrations that could otherwise lead toundesirable short term emissions levels.

The fuel from buffer tank 55 is used to run engine 61, which isconnected to generator 63. Together, engine 61 and generator 63 form agenerator that is run on the fuel to produce electricity. Engine 61 is amarine diesel engine designed to run on bunker fuel and the temperaturein reactor 23 is controlled by monitoring the fuel entering condenser 37so as to achieve the correct fuel specifications for engine 61. Bycombining the fuel generation process with the electricity generation ina single process, the fuel specification can be relaxed. Engine 61 canbe selected based in part on its ability to handle fuel of varyingspecification with the result that the acceptable specification for thefuel in buffer tank 55 can be broader than if the fuel was to be sold ascommercial fuel.

The engine 61 requires cooling and generates hot exhaust gases. The heatfrom those streams can be captured and used elsewhere in the hostfacility. In this embodiment, the heat is used in dryer and also inother processes in the host facility. Thus the process provides combinedheat and power to the facility. Cooling water circulates through theengine in cooling water line 65. The cooling water cools the engine 61,and is heated in that process. The cooling water then passes to heatexchanger 67, where it is cooled by indirect contact with cool waterentering heat exchanger 67 along line 69. The cooled cooling water exitsheat exchanger 67 and returns to the engine 61 to repeat the cycle. Thewater heated in the heat exchanger 67 exits along line 69 and is used toprovide heat to the dryer 15 and also to other processes in the hostfacility. The hot exhaust from the engine 61 is cooled by indirectcontact with an air stream in heat exchanger 73. The exhaust gases exitthe engine 61 along exhaust line 71 and pass through the heat exchanger73. Air stream 77 also passes through heat exchanger 73 and heat ispassed from the exhaust to the air stream. The exhaust gases thencontinue along exhaust line 71, through filter 75 to remove contaminantsand particulates and are vented to the atmosphere. The air stream 77that has been heated in heat exchanger 73 is directed to the dryer 15,where the heat in the stream is used to dry the incoming waste, and alsoto other processes in the host facility that use heat.

Whilst the present invention has been described and illustrated withreference to particular embodiments, it will be appreciated by those ofordinary skill in the art that the invention lends itself to manydifferent variations not specifically illustrated herein. By way ofexample only, certain possible variations will now be described.

Engine 61 and generator 63 may be replaced by other generator systems.For example, in some embodiments a turbine may be used. In someembodiments two generators are provided. A small generator runscontinuously to provide a base level of electrical power to run theremainder of the recycling facility in which the apparatus is installed.A large generator is turned on when the national electricity gridrequires short-term supplies of electricity. The large generator isselected so as to have a quick start-up cycle so as to benefit from thehigher price that national grids are willing to pay for electricalgenerating capacity that is available at short notice.

In some embodiments the de-watering press 5, shredder 9 and filter 13are provided in a different order. In some embodiments the waste may beshredded first and then de-watered and filtered. In other embodimentsthe three steps may be performed in other orders.

In some embodiments the de-watering press 5 is replaced by anotherde-watering system such as a de-watering centrifuge.

In some embodiments, the fuel gas that is heated to be fed back into thereactor 23 via line 45 in order to heat the incoming waste is drawn fromupstream of the hot gas filter 33. The volume of gas passing through thehot gas filter 33 in such embodiments is reduced as a result.

In some embodiments the waste fed to the process comprises Mixed PlasticWaste, but also comprises organic material. In some embodiments thewaste is Municipal Solid Waste.

In some embodiments the fuel burners 51 and 53 are replaced orsupplemented by burners designed to burn the char separated from thefluidised bed sand in cleaner 27. In that way the char by-product of thepyrolysis process is used to heat the reactor 23.

In some embodiments the buffer tank is a plurality of intermodal “20 ft”tank containers. In an example process, 1 tonne (1000 kg) per hour ofwaste may be fed to the process and 850 kg per hour of fuel produced bythe reactor. A single “20 ft” tank container provides enough storage foraround 24 hours of operations with the generator off, for example if thegenerator is undergoing maintenance.

In another example embodiment the fluidised bed reactor has a 1.5 mdiameter and a 1:1 aspect ratio (diameter to height ratio). The reactorcontains 3 tonnes of sand.

Where in the foregoing description, integers or elements are mentionedwhich have known, obvious or foreseeable equivalents, then suchequivalents are herein incorporated as if individually set forth.Reference should be made to the claims for determining the true scope ofthe present invention, which should be construed so as to encompass anysuch equivalents. It will also be appreciated by the reader thatintegers or features of the invention that are described as preferable,advantageous, convenient or the like are optional and do not limit thescope of the independent claims. Moreover, it is to be understood thatsuch optional integers or features, whilst of possible benefit in someembodiments of the invention, may not be desirable, and may therefore beabsent, in other embodiments.

The invention claimed is:
 1. A mixed plastic waste recycling apparatusconfigured for conversion of mixed plastic waste into a liquidhydrocarbon product, wherein the mixed plastic waste recycling apparatuscomprises: a fluidised bed pyrolysis reactor for pyrolysing the mixedplastic waste to produce a pyrolysis product, wherein the fluidised bedpyrolysis reactor is configured to contain a fluidised bed ofparticulate material; a condenser for condensing the pyrolysis productto form a liquid fraction and a gas fraction; a monitor for measuring anattribute of the liquid fraction related to heat of combustion; and acontroller for adjusting at least one of: i) a temperature of thefluidised bed of the fluidised bed pyrolysis reactor, and ii) aresidence time in the fluidised bed of the fluidized bed pyrolysisreactor, in response to the measured attribute of the liquid fraction soas to maintain the attribute within a desired range.
 2. The mixedplastic waste recycling apparatus according to claim 1, wherein theapparatus comprises a generator configured to run on the liquidfraction.
 3. The mixed plastic waste recycling apparatus according toclaim 2, wherein the generator comprises an internal combustion engineand/or a gas turbine.
 4. The mixed plastic waste recycling apparatusaccording to claim 1, wherein the apparatus further comprises a storagevessel upstream of the fluidised bed pyrolysis reactor for storing thewaste prior to feeding the mixed plastic waste to the fluidised bedpyrolysis reactor, wherein the storage vessel comprises a blendingsystem for blending the mixed plastic waste stored in the vessel.
 5. Themixed plastic waste recycling apparatus according to claim 1, whereinthe apparatus further comprises a dryer upstream of the fluidised bedpyrolysis reactor for drying the waste.
 6. The mixed plastic wasterecycling apparatus according to claim 1, wherein the monitor is asolvent monitor.
 7. The mixed plastic waste recycling apparatusaccording to claim 1, wherein the apparatus further comprises acombustor to combust a product from the fluidised bed pyrolysis reactorto heat a fluid that is fed into the fluidised bed pyrolysis reactor toheat the fluidised bed of the fluidised bed pyrolysis reactor.
 8. Themixed plastic waste recycling apparatus according to claim 1, whereinthe apparatus is sized and configured to treat from 5,000 to 20,000tonnes per year of mixed plastic waste.
 9. The mixed plastic wasterecycling apparatus according to claim 1, wherein the apparatus furthercomprises a distributor for feeding a fluidisation medium into thefluidised bed pyrolysis reactor, wherein the distributor is configuredsuch that the particulate material can fall through the distributor,wherein the fluidised bed pyrolysis reactor further comprises: an outletthrough which, in use, a portion of the particle material that hasfallen through the distributor can be removed; an apparatus forreheating and cleaning the removed particulate material; and an inletthrough which the reheated and cleaned particulate material can be fedback into the fluidised bed pyrolysis reactor, wherein the inlet islocated above the distributor.
 10. The mixed plastic waste recyclingapparatus according to claim 9, wherein the distributor furthercomprises an array of ducts with orifices in their surface and whereinthe ducts in the array are spaced apart such that, in use, theparticulate material can fall between the ducts.
 11. The mixed plasticwaste recycling apparatus according to claim 1, wherein the mixedplastic waste recycling apparatus further comprises a tank for storingthe liquid fraction as a liquid, a solid, or a mixture of a liquid and asolid.
 12. The mixed plastic waste recycling apparatus according toclaim 1, wherein the monitor for measuring an attribute of the liquidfraction related to heat of combustion is a monitor for measuringhydrocarbon chain length of the liquid fraction, and wherein thecontroller is for adjusting at least one of: i) the temperature of thefluidised bed of the fluidised bed pyrolysis reactor, and ii) theresidence time in the fluidised bed of the fluidised bed pyrolysisreactor in response to the measured hydrocarbon chain length of theliquid fraction so as to maintain hydrocarbon chain length of the liquidfraction within a desired range.
 13. The mixed plastic waste recyclingapparatus according to claim 1, wherein the fluidised bed of thefluidised bed pyrolysis reactor has at least one of 1) a mass of 2.5 to3.5 tonnes, and 2) an aspect ratio (height:width) of about 1:1.
 14. Themixed plastic waste recycling apparatus according to claim 1, whereinthe fluidised bed pyrolysis reactor is sized and configured to treatabout 1,000 kg of waste per hour.
 15. A comingled plastics recyclingapparatus configured for conversion of comingled plastics into ahydrocarbon product, wherein the comingled plastics recycling apparatuscomprises: a fluidised bed pyrolysis reactor for pyrolysing thecomingled plastics to produce a pyrolysis product, the fluidised bedpyrolysis reactor being configured to contain a fluidised bed ofparticulate material; a condenser for condensing the pyrolysis productto form a liquid fraction; a monitor for measuring an attribute of theliquid fraction related to heat of combustion; a controller foradjusting at least one of: i) a temperature of the fluidised bed of thefluidised bed pyrolysis reactor, and ii) a residence time in thefluidised bed of the fluidised bed pyrolysis reactor, in response to themeasured attribute related to heat of combustion of the liquid fractionso as to maintain the attribute within a desired range.
 16. Thecomingled plastics recycling apparatus according to claim 15, whereinthe apparatus further comprises a tank for storing the liquid fractionas a liquid, a solid, or a mixture of a liquid and a solid.
 17. Thecomingled plastics recycling apparatus according to claim 15, whereinthe apparatus further comprises a filter system for filtering thepyrolysis product to remove chemical contaminants.
 18. The comingledplastics recycling apparatus according to claim 17, wherein the filtersystem comprises a hot gas filter.
 19. The comingled plastics recyclingapparatus according to claim 15, wherein the apparatus further comprisesa storage vessel upstream of the fluidised bed pyrolysis reactor forstoring the comingled plastics prior to feeding the comingled plasticsto the fluidised bed pyrolysis reactor and wherein the storage vesselcomprises a blending system for blending the comingled plastics storedin the vessel.
 20. The comingled plastics recycling apparatus accordingto claim 15, wherein the apparatus further comprises a dryer upstream ofthe fluidised bed pyrolysis reactor for drying the comingled plastics.21. The comingled plastics recycling apparatus according to claim 15,wherein the apparatus further comprises a combustor to combust a productfrom the fluidised bed pyrolysis reactor to heat a fluid that is fedinto the fluidised bed pyrolysis reactor to heat the fluidised bed ofthe fluidised bed pyrolysis reactor.
 22. The comingled plasticsrecycling apparatus according to claim 15, further comprising adistributor for feeding a fluidisation medium into the fluidised bedpyrolysis reactor, wherein the distributor is configured such that theparticulate material can fall through the distributor and wherein thefluidised bed pyrolysis reactor further comprises: an outlet throughwhich, in use, a portion of the particulate material that has fallenthrough the distributor can be removed; an apparatus for reheating andcleaning the removed particular material; and an inlet through which thereheated and cleaned particulate material can be fed back into thefluidised bed pyrolysis reactor, wherein the inlet is located above thedistributor.
 23. The comingled plastics recycling apparatus according toclaim 15, wherein the monitor for measuring an attribute of the liquidfraction related to heat of combustion is a monitor for measuringhydrocarbon chain length of the liquid fraction, and wherein thecontroller is for adjusting at least one of: i) the temperature of thefluidised bed of the fluidised bed pyrolysis reactor, and ii) theresidence time in the fluidised bed of the fluidised bed pyrolysisreactor, in response to the measured hydrocarbon chain length of theliquid fraction so as to maintain hydrocarbon chain length of the liquidfraction within a desired range.
 24. The comingled plastics recyclingapparatus according to claim 23, wherein the controller is configured tomaintain hydrocarbon chain length of the liquid fraction in the range C₅to C₄₀.
 25. The comingled plastics recycling apparatus according toclaim 15, wherein the apparatus is sized and configured to treat from5,000 to 20,000 tonnes per year of mixed plastic waste.
 26. Thecomingled plastics recycling apparatus according to claim 15, whereinthe fluidised bed of the fluidised bed pyrolysis reactor has at leastone of 1) a mass of 2.5 to 3.5 tonnes, and 2) an aspect ratio(height:width) of about 1:1.
 27. The comingled plastics recyclingapparatus according to claim 15, wherein the fluidised bed pyrolysisreactor is sized and configured to treat about 1,000 kg of waste perhour.